I thought it was extremely well-done, for several reasons: Bedaker was a selfish, petty man, and David Wayne (who played him) made it clear exactly how he was destroyed by his own selfishness and pettiness. Cadwallader’s scenery-chewing was magnificent, and the episode made a strong point that one who longs for immortality may have no idea what it means or what to do with it.
I also admire the way that this (very) short story handles it: http://ficly.com/stories/1456
It is definitely a cautionary tale. The short story you linked is very similar and also cautionary.
If you’re immortal, at the end of time, there is no one left but you.
There is no worse Hell than that.